Bimetallic static gasket and method of construction thereof

ABSTRACT

A static gasket and method of construction thereof is provided. The gasket includes a functional layer constructed of one type of metal having an opening bounded by an inner periphery an outer periphery. The gasket further includes a carrier layer constructed of a different metal than the functional layer. The carrier layer has an opening bounded by an inner periphery configured to receive the outer periphery of the functional layer in a line-to-line or loose fit. The functional layer is configured in substantially coplanar relation with the carrier layer with a first portion of the outer periphery of the functional layer being welded to a radially aligned first portion of the inner periphery of the carrier layer. A second portion of the outer periphery of the functional layer remains detached from a radially aligned second portion of the inner periphery of the carrier layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This continuation application claims priority to U.S. application Ser.No. 15/371,426, filed Dec. 7, 2016, which claims the benefit of U.S.Utility application Ser. No. 12/854,626, filed Aug. 11, 2010, now U.S.Pat. No. 9,518,660, issued Dec. 13, 2016, which claims the benefit ofU.S. Provisional Application Ser. No. 61/233,003, filed Aug. 11, 2009,all of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION 1. Technical Field

This invention relates generally to static gaskets of the type used toestablish a gas/fluid-tight seal between two members to be clampedtogether, and more particularly to exhaust manifold gaskets.

2. Related Art

In establishing a gas/fluid-tight seal between two members to be clampedtogether, such as between cylinder block and engine block or an exhaustmanifold and engine block, it is common to use a static gasket having asingle layer of a single piece of material, or a plurality of stackedlayers overlying one another formed as a multilayer gasket. Generally,at least one of the layers of the multilayer gasket, sometimes referredto as a functional layer, has a seal bead to facilitate establishing agas/fluid tight seal about an opening. The functional layer needs to befabricated of a material suitable for establishing and maintaining thegas/fluid tight seal, and further, typically needs to be able towithstand high temperature environments. As such, the functional layermaterial needs to constructed from a high quality metal, typicallycoming at a relatively high cost. As such, use of the high costfunctional layer material increases the overall cost of the gasket, andin addition, typically results in high cost waste material.

In addition, to minimized the possibility of over compressing the sealbead of the functional layer, a stopper layer in a multilayer gasketneeds to be constructed of a predetermined thickness material to ensurethe bead or beads remain functional. Unfortunately, metal sheet materialtypically used as stopper layer material is produced having a generallywide thickness tolerance, such as about +/−0.001″, and thus, it can bedifficult to tightly control the stopper height, wherein the stopperheight is provided by the material thickness. As such, to avoid overcompression of the seal bead in the functional layer, the manufacturertypically errors on the side of having a thicker stopper layer than maybe necessary in order to account for inherent manufacturing tolerancefluctuations. Unfortunately, this also adds cost to the gasket assembly.

SUMMARY OF THE INVENTION

A static gasket for providing a gas/fluid tight seal between a membersto be clamped together is provided. The gasket includes at least onemetal functional layer constructed of one type of metal with eachfunctional layer having an opening bounded by an inner peripheryconfigured to register circumferentially with an opening to be sealedand having an outer periphery. The gasket further includes at least onemetal carrier layer constructed of a different metal than the at leastone functional layer. Each carrier layer has an opening bounded by aninner periphery configured to receive the outer periphery of the atleast one functional layer in a line-to-line or loose fit. The at leastone functional layer is configured in substantially coplanar relationwith the at least one carrier layer with a first portion of the outerperiphery of the at least one functional layer being welded to aradially aligned first portion of the inner periphery of the at leastone carrier layer via a butt weld joint. A second portion of the outerperiphery of the at least one functional layer remains detached from aradially aligned second portion of the inner periphery of the at leastone carrier layer.

In accordance with another aspect of the invention, the carrier layerhas a material thickness established between opposite planar surfaceswith at least one of the planar surfaces having raised projectionsformed of the carrier metal material, wherein the raised projectionsprovide a thickness across the opposite planar surfaces that is greaterthan the material thickness of the carrier metal layer.

According to one aspect of the invention, the functional layer has anembossed sealing bead extending circumferentially about its opening andthe carrier layer is substantially flat.

According to another aspect of the invention, the carrier layer has atleast one through passage radially outwardly from and adjacent itsopening for receipt of a swaging tool during assembly.

According to another aspect of the invention, weld joints formedradially inwardly of the carrier layer through passage attach the firstand second layers to one another.

According to another aspect of the invention, the gasket has a pair ofcarrier layers overlying one another with at least of the functionallayers attached to each carrier layer, thereby providing a multilayergasket assembly.

In accordance with yet another aspect of the invention, a method ofconstructing a static gasket is provided. The method includes providingfirst and second layers of metal constructed of different types of metalfrom one another and forming the first layer into a functional layerhaving an opening configured to register circumferentially with anopening to be sealed and having an outer periphery and forming thesecond layer into a carrier layer having an opening bounded by an innerperiphery configured to receive the outer periphery of the functionallayer therein. Further, disposing the outer periphery of the functionallayer in the opening of the carrier layer such that the functional layeris in substantially coplanar relation with the carrier layer. Furtheryet, biasing a portion of the inner periphery of the carrier layer intoabutment with a radially aligned portion of the outer periphery of thefunctional layer, and then, welding the portion of the inner peripheryof the carrier layer to the radially aligned portion of the outerperiphery of the functional layer.

According to another aspect of the invention, the method furtherincludes forming a plurality of raised projections about the opening inthe carrier layer and, disposing the outer periphery of the functionallayer in the opening of the carrier layer.

According to another aspect of the invention, the method furtherincludes coining the raised projections.

According to another aspect of the invention, the method furtherincludes extruding the raised projections.

According to another aspect of the invention, the method furtherincluding fixing the outer periphery of the functional layer to theinner periphery of the carrier layer by forming a weld joint extendingtherebetween.

According to another aspect of the invention, the method furtherincludes forming a through passage adjacent the opening in the carrierlayer and swaging the carrier layer to bring the inner periphery of thecarrier layer into abutment with the outer periphery of the functionallayer prior to forming the weld joint therebetween.

According to yet another aspect of the invention, the method includesproviding a pair of carrier layers overlying one another and attachingat least one of the functional layers to each carrier layer to provide amultilayer gasket assembly.

According to yet another aspect of the invention, the method furtherincludes fixing the pair of carrier layers to one another radiallyoutwardly from the openings formed therein.

According to yet another aspect of the invention, the method furtherincludes fixing a pair of the functional layers to a single one of thecarrier layers.

According to yet another aspect of the invention, the method furtherincludes forming sealing beads in the functional layers.

According to yet another aspect of the invention, the method includesforming the functional layer with a relatively high cost gasket qualitymetal and forming the carrier layer with a relatively low cost metal.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of a static gasketconstructed in accordance with the invention will become more readilyappreciated when considered in connection with the following detaileddescription of presently preferred embodiments and best mode, appendedclaims and accompanying drawings, in which:

FIG. 1 is a perspective view of an exhaust manifold gasket assemblyconstructed in accordance with one aspect of the invention;

FIG. 2 is a cross-sectional side view taken generally along line 2-2 ofFIG. 1;

FIG. 2A is a cross-sectional side view taken generally along line 2A-2Aof FIG. 1;

FIG. 3 is plan view of a sealing portion of the gasket of FIG. 1 priorto attaching the sealing portion to a non-sealing portion of the gasket;

FIG. 4 is a cross-sectional side view taken generally along line 4-4 ofFIG. 3;

FIG. 5A is a partial view of a swaging tool being used in constructionof a gasket constructed in accordance with one aspect of the inventionwith the swaging tool shown in a pre-engaged position; and

FIG. 5B is a view similar to FIG. 5A showing the swaging tool in anengaged position.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

Referring in more detail to the drawings, FIG. 1 illustrates abimetallic static gasket assembly 10, referred to hereafter as gasket,constructed in accordance to one aspect of the invention. The gasket 10can be constructed as a single layer gasket of dissimilar first andsecond materials welded to one another, or as shown here, by way ofexample and without limitation, as a multilayer gasket. The gasket 10has at least one, and shown here as three functional layer inserts, alsoreferred to as functional layers or first layers 12, and at least one,and shown here as a pair of carrier layers, also referred to as secondlayers 14, 15. The carrier layer or layers 14, 15 can be configured tocarry a plurality of the functional layers 12 spaced laterally from oneanother at different locations of the carrier layers 14, 15 depending onhow many openings need to be sealed in the application. Respective onesof the functional layers 12 and carrier layers 14, 15 are fixed to oneanother in planar or substantially planar relation with one another,wherein the functional layers 12 have sealing beads, represented here ashalf beads 16, by way of example, to establish a gas/fluid tight sealabout an opening 18 to be sealed, such as between an engine block and anexhaust manifold, for example, wherein the carrier layers 14, 15function to carry and locate the functional layers 12 during assembly.With the functional layers 12 acting to establish the seal about theopening 18 or openings 18 to be sealed, the material used to constructthe functional layers 12 is a high quality gasket metal, such as aspring steel, stainless steel or other high temperature alloy, forexample. Accordingly, the material used to construct the functionallayers 12 is relatively expensive compared to more standard, low gradesteel material. In contrast, with the carrier layers 14, 15 acting ascarriers of the functional layers 12, the material used to construct thecarrier layers is a comparatively low cost metal, such as a low gradesteel or aluminum, for example. Accordingly, the material used toconstruct the carrier layers 14, 15 is relatively inexpensive incomparison to the material used to construct the functional layers 12.As such, the gasket 10 provides an ability to form a reliable seal aboutthe openings 18, while at the same time being economical in manufacture,having low cost material working in combination with high cost material,and in use. In addition, the cost associated with the waste generatedfor the high cost material is minimized, further reducing the costassociated with manufacture of the gasket 10.

The functional layers 12, being constructed from a resilient metal, suchas spring steel, for example, are provided having a thickness of about0.1 to 0.3 mm, for example. Two of the functional layers 12, as shown inFIG. 2, by way of example and without limitation, are constructed havingmirrored profiles to one another. Each functional layer 12 has an innerperiphery 20 configured to register concentrically and in axialalignment with the opening 18 and an outer periphery 22 with half beads16 extending between the inner and outer peripheries 20, 22. The halfbeads 16 converge toward one another into abutment with one anotheralong inner plateau regions 24 adjacent the inner periphery 20 anddiverge away from one another to outer plateau regions 26 spaced axiallyfrom one another a predetermined distance adjacent the outer periphery22. The third functional layer 12, shown in FIG. 2 as being thelowermost functional layer 12, is constructed having a mirrored profilein relation to the adjacent, intermediate sandwiched functional layer12. Accordingly, the lowermost functional layer 12 has an innerperiphery 20′ configured to register concentrically and in axialalignment with the opening 18 and an outer periphery 22′ with a halfbead 16′ extending between the inner and outer peripheries 20′, 22′. Thehalf beads 16, 16′ of the intermediate and lowermost functional layers12 diverge away from one another to respective inner plateau regions 24,24′ adjacent the inner peripheries 20, 20′ and converge toward oneanother into abutment with one another along outer plateau regions 26,26′ adjacent the outer peripheries 22, 22′. The combined functionallayers 12, and thus their inner plateau regions 24, 24′, have a combinedtotal thickness that is substantially the same as the thickness of thesingle carrier layer 15.

As shown in FIG. 2, the uppermost carrier layer 14 has an opening 28bounded by an inner periphery 30 configured to receive the outerperiphery 22 of the functional layer 12 in close, line-to-line orslightly loose relation therein and an outer periphery 32 (FIGS. 1 and2A). To facilitate fixing the functional layer 12 to the carrier layer14, discussed in further detail below, the carrier layer 14 has at leastone, and shown here as a pair of through passages 34 adjacent the innerperiphery 30 and shown here as being diametrically across the opening28, for example. The through openings 34 extend a predetermined distancegenerally parallel to the inner periphery 30, and are preferablyelongate and generally rectangular in shape.

The lowermost carrier layer 15 is generally shaped the same as theuppermost carrier layer 14, however, for reasons discussed hereafter,has a slightly increased thickness (t) in comparison to the uppermostsecond layer 14. As such, the lowermost carrier layer 15 has an opening28′ bounded by an inner periphery 30′ configured to receive the outerperipheries 22, 22′ of the intermediate and lowermost functional layers12 in close, line-to-line or slightly loose relation therein and anouter periphery 32′. To facilitate fixing the functional layer 12 to thecarrier layer 15, the carrier layer 15 has at least one, and shown hereas a pair of through passages 34′ adjacent the inner periphery 30′ andshown here as being diametrically across the opening 28′ and configuredto register with the through openings 34 in the uppermost carrier layer14.

To complete the construction of the gasket 10, upon forming the featuresdiscussed above in the individual layers 12, 14, 15, the functionallayers 12 are disposed in the openings 28, 28′ of the carrier layers 14,15 so that the outer peripheries 22, 22′ are received within the innerperipheries 30, 30′ of the carrier layers 14, 15. Upon being disposedtherein, the outer plateau regions 26, 26′ of the functional layers 12are configured in coplanar or substantially coplanar relation with therespective carrier layers 14, 15, as shown. The outer peripheries 22,22′ of the functional layers 12 are brought into a close, line-to-lineor a slightly loose fit relative to the inner peripheries 30, 30′ of thecarrier layers 14, 15, such that a gap 42 between about 0.000-0.010″,for example, is established there between. Then, upon positioning thefunctional layers 12 within the openings 28, 28′ of the carrier layers14, 15, as shown in FIG. 5A (showing only carrier layer 15 being weldedto mirrored intermediate and lowermost functional layers 12, wherein thesame process is used to weld the carrier layer 14 to the uppermostfunctional layer 12), a swaging tool 44 having a camming surface 45 isinserted into the through passages 34 to bias a first portion of theinner peripheries 30, 30′ located radially inwardly and in radialalignment with the through passages 34 into abutment with adjacent firstportions of the outer peripheries 22, 22′ of the functional layers 12(FIG. 5B, swaging tool 44 engaged). Accordingly, the first portions ofthe carrier layers 14, 15 are plastically biased radially inwardly intoabutment with radially aligned first portions of the functional layers12, while the second portions (portions other than those plasticallybiased by the swaging tool 44) of the carrier layers 14, 15 remainunbiased and spaced with radially aligned second portions of thefunctional layers 12. Then, as shown in FIG. 2A, weld joints, such aslaser weld joints 36 are formed to fix the respective first portions ofthe inner peripheries 30, 30′ of the carrier layers 14, 15 to the firstportions of the outer peripheries 22, 22′ of the functional layers 12,while the circumferentially outlying second portions of the functionallayers 12 and the carrier layers 14, 15 remain detached from oneanother, such that the gaps 42 remain therebetween. The resulting laserbutt weld joints 36 can be formed using a continuous or pulse laserprocess, as desired. Further, the butt weld joints 36 can be formed ascontinuous or intermittent weld joints. In addition to the weld joints36 fixing the functional layers 12 to the carrier layers 14, 15,additional weld joints, such as laser spot weld joints 46, for example,can be formed to fix the separate, overlying carrier layers 14, 15 toone another at selected locations to form the unitized gasket assembly10, such that the functional layers 12 and carrier layers 14, 15 are allfixed to one another. Further yet, additional weld joints, such as laserspot weld joints 48, for example, can be formed to fix abutting portionsof the functional layers 12 to one another. The spot weld joints 48 areshown in FIG. 2 as being formed between the inner plateau regions 24 andalso between the outer plateau regions 26, 26′. The functional layers 12can be welded to one another prior to or after being welded to thecarrier layers 14, 15.

In accordance with another aspect of the invention, to preventover-compression of the beads 16 of the functional layer 12, the carrierlayer 14 has a plurality of raised projections 50 extending about theopenings 18, wherein the projections 50 are formed having apredetermined, tight tolerance height (h1) to prevent the beads 16 frombeing completely flattened upon compressing the gasket 10 between thesurfaces to be sealed. Further, the raised projections 24 can be formedabout fastener openings 52 having a predetermined, tight toleranceheight (h2) to facilitate creating the desired load distribution throughthe gasket 10. The projections 50 are formed extending about orsubstantially about the openings 28, 28′, wherein the projections 50 canbe formed with their height (h1) being constant, wherein the height ismeasured from the planar surface adjacent from which the projections 50extend outwardly from to a peak of the projections 50, or their height(h1) can vary about the openings 28, 28′, either continuously or inpredetermined sectors, to achieve a predetermined compressiondistribution applied to the half beads 16 of the functional layers 12.It should be recognized that the projections 20 can be formed to extendfrom one side, such as shown for the upper carrier layer 14, or fromboth of the sides, such as shown for the lower carrier layer 15,depending on the application and construction of the gasket 10.

The projections 50 are formed by upsetting the material of the carrierlayers 14, 15, such as in a coining or extruding process, for example.The projections 50, aside from being able to formed of constant heightsor varying heights (h1), can be formed having any desired geometricshape, such that when viewed from overhead, can be circular, square,rectangular, hexagonal, pyramidal, or any other suitable shape.

In addition to the projections 50 formed about the openings 28. 28′,projections 50 are also formed about the fastener openings 52. Theprojections 50 formed about the fastener openings 52 can be formedhaving the same height as the height of the projections 50 formed aboutthe openings 28, 28′, such that h2 is equal to h1, or the heights can bedifferent, such that h2 is different from h1. Accordingly, precisecontrol can be obtained for the clamping load throughout the gasket 10,thereby maximizing the ability to maintain a gas/fluid tight seal aboutthe openings 18 to be sealed.

With the projections 50 limiting the degree of compression applied tothe beads 16, 16′, the thickness t1 of the sheet material used toconstruct the carrier layers 14, 15 can be the same as or substantiallythe same as the thickness of the material used to construct thefunctional layers 12. Accordingly, the cost of the material used toconstruct the carrier layers 14, 15 can be minimized. Further, with theprojections 50 providing a stopper limiting the degree of compression tothe beads 16, 16′, the stopper has a tightly controlled tolerance,thereby allowing the compression of the beads 16, 16′ to be tightlycontrolled, thus, further facilitating the formation of a gas/fluidtight seal. It should be recognized that the processes used to producethe projections 50 can provide a very tight tolerance for the height ofthe projections 50 that is significantly tighter than the tolerance ofthe material thickness t1.

In accordance with another aspect of the invention, to facilitateorienting the functional layers 12 relative to the carrier layers 14, 15prior to establishing the weld joints 36, the functional layers 12 canbe formed having an inner webbing 38 extending across the opening 18between the diametrically opposite portions of the inner periphery 20,20′. The webbing 38 is for assembly purposes only, and is subsequentlyremoved upon assembly, such as in a laser cutting process, for example.The webbing has a pair of locator openings 40 formed therein, whereinthe locator openings 40 are configured for receipt of a locator fixtureor posts therein. Upon disposing the locator posts in the locatoropenings 40, the functional layers 12 are automatically aligned properlywithin the openings 28, 28′ of the carriers 14, 15. As such, the weldingprocess, including swaging and subsequent welding can then be performed.Upon forming the weld joints 36, the webbing 38 can then be removed, asdiscussed above, such as in a laser cutting process.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed is:
 1. A method of constructing a static gasket,comprising: providing first and second layers of metal constructed ofdifferent types of metal from one another; forming the first layer intoa functional layer having an opening configured to registercircumferentially with an opening to be sealed and having an outerperiphery; forming the second layer into a carrier layer having anopening bounded by an inner periphery configured to receive the outerperiphery of the functional layer therein; disposing the outer peripheryof the functional layer in the opening of the carrier layer such thatthe functional layer is in substantially coplanar relation with thecarrier layer; forming at least one through passage in the carrierlayer; extending a swaging tool into the through passage to plasticallydeform a first portion of the carrier layer and bias the inner peripheryof the first portion of the carrier layer into abutment with a radiallyaligned portion of the outer periphery of the functional layer whilesecond portions of the carrier layer that are not biased by the swagingtool remain unbiased; and welding the portion of the inner periphery ofthe first portion of the carrier layer to the radially aligned portionof the outer periphery of the functional layer.
 2. The method as setforth in claim 1 further including leaving radially aligned portions ofthe inner periphery of the carrier layer and the outer periphery of thefunctional layer detached from one another.
 3. The method as set forthin claim 1 further including forming raised projections in the carrierlayer about the opening in the carrier layer material, wherein theraised projections provide a thickness across opposite planar surfacesof the carrier layer that is greater than the material thickness of thecarrier layer.
 4. The method as set forth in claim 3 further includingthe step of forming at least one sealing bead into the functional layer.5. The method as set forth in claim 4 wherein the at least one sealingbead has a first height and wherein a plurality of the projections ofthe carrier layer have a second height which is less than the firstheight.
 6. The method as set forth in claim 5 wherein the functionallayer is a first functional layer and further including the step offorming a second functional layer and wherein each of the first andsecond functional layers has at least one sealing bead.
 7. The method asset forth in claim 6 wherein each of the at least one sealing bead ineach of the first and second functional layers is a half bead andwherein the half beads of the first and second functional layers areradially aligned with one another.
 8. The method as set forth in claim 7further including the step of welding the first and second functionallayers together.
 9. The method as set forth in claim 8 further includingthe step of forming a third functional layer with a half bead which isradially aligned with the half beads of the first and second functionallayers.
 10. The method as set forth in claim 9 further including thestep of welding the third functional layer with one of the first andsecond functional layers.
 11. The method as set forth in claim 10wherein the first and second functional layers are welded together onone radial side of the aligned half beads and wherein the thirdfunctional layer is welded to the first functional layer or the secondfunctional layer on an opposite radial side of the aligned half beads.12. The method as set forth in claim 9 wherein the carrier layer is afirst carrier layer and further including the step of forming a secondcarrier layer.
 13. The method as set forth in claim 12 further includingthe step of biasing a portion of an inner periphery of the secondcarrier layer into abutment with a radially aligned portion of an outerperiphery of the third functional layer.
 14. The method as set forth inclaim 13 further including the step of welding the portion of the innerperiphery of the second carrier layer to the outer periphery of thethird functional layer.
 15. The method as set forth in claim 3 furtherincluding forming a plurality of fastener openings in the carrier layerand forming the raised projections about the plurality of fasteneropenings.
 16. The method as set forth in claim 15 further including thestep of forming the raised projections about the opening in the carrierlayer and wherein some of the raised projections have different heights.17. The method as set forth in claim 1 further including forming a pairof functional layers having outer peripheries received in a singlecarrier layer inner periphery.
 18. The method as set forth in claim 17further including forming the pair of functional layers having acombined thickness and the single carrier layer having a thickness thatis substantially equal to the combined thickness.